The present invention disclosed herein relates to a semiconductor device and a manufacturing method thereof, and more particularly, to a photomultiplier and a manufacturing method thereof.
A semiconductor optical sensor may include an avalanche photodiode detecting weak light. The avalanche photodiode may highly sensitively detect light by avalanche multiplication accelerating electron-hole pairs. Research and development into a semiconductor photomultiplier, which is operated in a voltage range exceeding a breakdown voltage and is fabricated to be able to detect very weak incident light, have been actively conducted based on such avalanche photodiode.
A photomultiplier may include cell diodes and quench resistors serially connected to the cell diodes. The quench resistors cause an ohmic voltage drop when an instantaneous current due to electrical breakdown flows in the microcell to drop a voltage applied to each cell diode below a breakdown voltage, and thus, may act to relieve a breakdown state.
In general, a cell diode formed of silicon may include a low concentration epitaxial silicon thin film on a bulk silicon layer in a high concentration doped layer. For example, microcell diodes may have doped structures such as p+/p−/n+, p+/n−/n+, n+/n−/p+, and n+/p−/p+.
Such microcell diodes having a simple structure may not be properly operated due to premature edge breakdown. A general photomultiplier may include a guard ring formed at an edge of the microcell diodes in order to prevent the premature edge breakdown.
However, since a typical method of manufacturing a photomultiplier requires a lithography process for forming a guard ring, productivity may decrease. For example, a silicon microcell diode may be formed through approximately three lithography processes including a mask alignment pattern, an upper doped layer pattern, and a guard pattern.